The present invention is directed to a novel method of encapsulating finely divided or micronized, substantially hydrophobic fluids using flash-flow, e.g. melt-spun techniques, to produce delivery systems for use in food products and other comestibles, pharmaceuticals, gum and confectionery products, cosmetics and personal hygiene products. More particularly, the present invention relates to a delivery system having a solid, hydrophilic encapsulating material capable of undergoing those changes associated with the flash-flow phenomena occurring during, for example, melt spinning and having a multitude of finely divided or micronized hydrophobic oil dispersed therein.
The use of hydrophobic oils of flavorants or fragrances in comestibles, pharmaceuticals, cosmetics and the like has focused on ways to control the organoleptic impact either by delaying or accelerating the intensity of perception. In conventional comestible products such as foods, pharmaceuticals, gum and confectioneries, flavor oils have been added in the free state, as well as in the encapsulated form for the combined effects of immediate and delayed flavor perception. For example, U.S. Pat. No. 4,485,118 to Carrol, et al. discloses a chewing gum composition which contains sequentially released plural flavor system. One of the flavors is encapsulated with a water-insoluble coating for delayed release and a separate flavor is introduced in free, uncoated form for immediate release. U.S. Pat. No. 3,962,463 to Witzel discloses a chewing gum having a reduced content of flavor ingredients, obtained by impregnating or depositing solid flavor particles, such as microencapsulated flavor particles sorbed on an edible substrate, and placing them on the surface of the gum.
In the comestible art, encapsulation and coating techniques have also focused on protecting the flavor oils from reacting with other co-mixed chemicals, or from oxidation, evaporation or volatilization through direct exposure to the environment. Flavor oils have been combined with a variety of sweeteners, particularly, for example, in gum and confectionery products. Flavor oils are often aldehyde, ketone and ester compounds which are highly reactive with a host of other common materials found in comestible products, as well as being sensitive to heat. For example, one such material commonly added to comestibles which reacts quickly to lose its sweetness in the presence of flavor oils is aspartame. The result is a comestible product which lacks both flavor and sweetness and therefore suffers from lack of overall organoleptic quality and shelf-life instability.
Methods of encapsulating or coating oils have conventionally involved using matrices of other hydrophobic materials, such as melted and solidified fats and waxes, polymers such as polyvinyl acetate and solvents, and/or elastomeric materials. Simple mixtures of these hydrophobic matrices and flavor and/or sweetener materials were prepared using solvents and/or heat to form a melt in order to incorporate the flavor oil into the matrix. Incorporation in the melted stage was required to obtain as much homogeneity and encapsulation as possible. The molten mass was then cooled to solidification and ground into particles.
U.S. Pat. No. 4,740,376 to Yang discloses use of a melted high molecular weight polyvinylacetate blended with a hydrophobic plasticizer and a flavoring ingredient. The melt blend is cooled, ground into a particulate and incorporated into an edible product. The hydrophobic plasticizers employed are mono-, di- and triglycerides having a fatty acid chain length of 16 to 22 carbons.
U.S. Pat. No. 4,722,845 to Cherukuri, et al. discloses stable cinnamon flavored chewing gum compositions comprising gum base, sweetener and a sweetener delivery system comprising a dipeptide or amino acid sweetener in a mixture of fat and high melting point (106.degree. C.) polyethylene wax. U.S. Pat. No. 4,803,022 also to Cherukuri, et al. discloses a powdered flavor composition encapsulated in a hydrophobic matrix of fat or wax and containing thaumatin, monellin or dihydrochalcones as the sweetener.
U.S. Pat. No. 4,824,681 to Schobel, et al. discloses an encapsulated sweetening agent which is protected from moisture and provides controlled release wherein the sweetening agent is encapsulated with a hydrophobic polymer and a hydrophobic plasticizer. Hydrophobic coating is also described in detail in U.S. Pat. No. 4,828,857 to Sharma, et al. wherein a delivery system is disclosed having as a core material a sweetener or flavoring ingredient and a protective matrix formed by a fluidized bed spray coating.
These processes involving the formation of molten hydrophobic mixtures having inherent disadvantages which include loss of volatile flavor components during the heating process and significant mixing requirements to ensure homogeneity. Separate grinding steps followed, which also generated vaporization of flavor components and, in the case of certain sensitive sweeteners, degradation and loss of sweetness. Additionally, simple mixtures have failed to provide adequate uniform coating protection to keep the core flavors and sweeteners in a sustained stabilized state. Other processes, in an attempt to improve over simple mixing techniques, have included spray congealing and fluidized bed spray coating. While these methods may overcome certain of the above-mentioned disadvantages, they still employ significant amounts of heat and/or solvents and plasticizers and do not result in micronized discrete flavor droplets within a matrix, but rather a non-uniform agglomeration of the flavor and/or sweetener with a hydrophobic carrier. See, for example, U.S. Pat. No. 4,722,845 to Cherukuri, et al. Coating of sweeteners and oils with hydrophobic materials also interferes with the immediate release properties and up-front, instantaneous flavor and/or sweetness impact.
The delivery systems of the present invention represents a departure from conventional methods and their resultant products in a number of important ways. To begin with, instead of using hydrophobic encapsulating matrix materials, flash-flowable hydrophilic materials are employed. These materials must be capable of undergoing flash-flow processes such as melt-spinning without significant degradation or burning. Therefore, instead of simple mixing and grinding, spray congealing and spray coating techniques, flash-flow processing as later defined herein, is employed. The result is a solid particulate which constitutes a highly water-soluble, flash-flowable matrix or encapsulant in which there is dispersed throughout fine, micronized liquid droplets. During the flash-flow process, the encapsulant is exposed to extremely limited conditions of heat and then usually only for a fraction of a second. This substantially lessens the potential for volatilization of certain hydrophobic liquid components. In the case of flavor oils, analytical testing has demonstrated that the intensive delivery systems retain more flavor components than those processes of the prior art.